Boarding School Juliet Vol. 7 (manga)

Dahlia Academy's first-years are away from their fair campus for a friendly three-day school trip, and surprising no one, it only takes one night for the fierce feud between the White Cats and Black Doggies to blow up yet again. This time, it's leading ladies Persia and Hasuki at each other's throats over Inuzuka's affections. They've vowed to prove once and for all which of them loves their dear Romio the most.